1. Field of the Invention
The present invention relates to a technology for press molding of preliminary molded or unmolded glass material with a mold die.
2. Related Background Art
Technologies for obtaining molded articles by press molding, with a mold die, of glass material softened by heating is already known for a long time for example from the U.S. Pat. Nos. 3,244,497, 3,294,878, 3,402,226 and 3,416,907, etc.
Also the method and apparatus for press molding with a mold die after heating of glass material were disclosed in the U.S. Pat. Nos. 3,833,347, 3,844,755, 3,900,328, 4,139,677 and 4,168,961.
Besides, in the field of technology related to the present invention, there were recently issued U.S. Pat. No. 4,591,373, 4,606,750, 4,629,487 and 4,629,489.
Also among the Japanese Laid-open and Published patents, the Japanese Patent Publication No. 56-378 discloses a method of heating glass material on a mold die and then molding the glass by pressing in said mold die. Also, the Japanese Laid-open Patent No. 60-239331 discloses an apparatus in which a lower mold die (7) is placed on a support carriage (6), and plural carriage (6) are mutually linked and guided, by means of a conveyor belt (4) to a molding furnace (8) consisting of a heating chamber (9), a molding changer (11) and a slow cooling chamber (12). Furthermore the Japanese Laid-open Patent No. 61-256929 and No. 62-191430 disclose an apparatus in which optical material is placed on a carrier and transported by transport means to a heating step and a pressing step for press molding.